There is little information about the actual nutrition and fluid intake habits, and gastrointestinal (GI) symptoms of athletes during endurance events. PURPOSE:: To quantify and characterize energy, nutrient and fluid intakes during endurance competitions and investigate associations with GI symptoms. METHOD:: 221 endurance athletes (male and female) were recruited from two Ironman triathlons (IM Hawaii and IM GER), a half-Ironman (IM70.3), a MARATHON, a 100/150 km CYCLE race. Professional cyclists (PRO) were investigated during stage-racing. A standardized post-race questionnaire quantified nutrient intake and assessed 12 GI symptoms on a scale from 0 (no problem) to 9 (worst it has ever been) in each competition. RESULTS:: Mean CHO intake rates were not significantly different between IM Hawaii, IM GER and IM70.3 (62±26, 71±25 g/h and 65±25 g/h, respectively), but lower mean CHO intake rates were reported during CYCLE (53±22 g/h, p=0.044) and MARATHON (35±26 g/h; p<0.01). Prevalence of serious GI symptoms were highest during the IM races (∼31%; p=0.001) compared with IM70.3 (14%), CYCLE (4%), MARATHON (4%) and in PRO (7%), and correlated to a history of GI problems. In all data sets scores for upper and lower GI symptoms correlated with reported history of GI distress (r=0.37 and r=0.51, respectively; p<0.001). Total CHO intake rates were positively correlated with nausea and flatulence but negatively correlated with finishing time during both IM (r=-0.55 and r=-0.48; p<0.001). CONCLUSION:: The present study demonstrates that CHO intake rates vary greatly between events and individual athletes (6-136 g/h). High CHO intake during exercise was related to increased scores for nausea and flatulence, but also to better performance during IM races.